كتاب الإيمان
1  
The Book of Faith
(73)
Chapter: The beginning of the revelation to the messenger of Allah (saws)
(73)
باب بَدْءِ الْوَحْىِ إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم ‏‏
Sahih Muslim 161 d

Yahya reported:

I asked Abu Salama what was revealed first from the Qur'an. He said:" 0, the shrouded one." I said: Or" Recite." Jabir said: I am narrating to you what was narrated to us by the Messenger of Allah (ﷺ). He said: I stayed in Hira' for one month and when my stay was completed, I come down and went into the heart of the valley. Somebody called me aloud. I looked in front of me, behind me, on the right of my side and on my left, but I did not see any body. I was again called and I looked about but saw nothing. I was called again and raised my head, and there on the Throne in the open atmosphere he, i. e. Gabriel (peace be upon him) was sitting. I began to tremble on account of fear. I came to Khadija and said: Wrap me up. They wrapped me up and threw water on me and Allah, the Exalted and Glorious, sent down this: you who are shrouded! arise and deliver warning, your Lord magnify, your clothes cleanse."
وَحَدَّثَنَا زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا الْوَلِيدُ بْنُ مُسْلِمٍ، حَدَّثَنَا الأَوْزَاعِيُّ، قَالَ سَمِعْتُ يَحْيَى، يَقُولُ سَأَلْتُ أَبَا سَلَمَةَ أَىُّ الْقُرْآنِ أُنْزِلَ قَبْلُ قَالَ يَا أَيُّهَا الْمُدَّثِّرُ ‏.‏ فَقُلْتُ أَوِ اقْرَأْ ‏.‏ فَقَالَ سَأَلْتُ جَابِرَ بْنَ عَبْدِ اللَّهِ أَىُّ الْقُرْآنِ أُنْزِلَ قَبْلُ قَالَ يَا أَيُّهَا الْمُدَّثِّرُ ‏.‏ فَقُلْتُ أَوِ اقْرَأْ قَالَ جَابِرٌ أُحَدِّثُكُمْ مَا حَدَّثَنَا رَسُولُ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ جَاوَرْتُ بِحِرَاءٍ شَهْرًا فَلَمَّا قَضَيْتُ جِوَارِي نَزَلْتُ فَاسْتَبْطَنْتُ بَطْنَ الْوَادِي فَنُودِيتُ فَنَظَرْتُ أَمَامِي وَخَلْفِي وَعَنْ يَمِينِي وَعَنْ شِمَالِي فَلَمْ أَرَ أَحَدًا ثُمَّ نُودِيتُ فَنَظَرْتُ فَلَمْ أَرَ أَحَدًا ثُمَّ نُودِيتُ فَرَفَعْتُ رَأْسِي فَإِذَا هُوَ عَلَى الْعَرْشِ فِي الْهَوَاءِ - يَعْنِي جِبْرِيلَ عَلَيْهِ السَّلاَمُ - فَأَخَذَتْنِي رَجْفَةٌ شَدِيدَةٌ فَأَتَيْتُ خَدِيجَةَ فَقُلْتُ دَثِّرُونِي ‏.‏ فَدَثَّرُونِي فَصَبُّوا عَلَىَّ مَاءً فَأَنْزَلَ اللَّهُ عَزَّ وَجَلَّ ‏{‏ يَا أَيُّهَا الْمُدَّثِّرُ * قُمْ فَأَنْذِرْ * وَرَبَّكَ فَكَبِّرْ * وَثِيَابَكَ فَطَهِّرْ‏}‏ ‏"‏ ‏.‏
Reference : Sahih Muslim 161d
In-book reference : Book 1, Hadith 314
USC-MSA web (English) reference : Book 1, Hadith 307
  (deprecated numbering scheme)